Process Optimization

Ash Fusibility Testing >
Grindability testing in mining: bond work index determination >
Iron Ore Reducibility Test >
Monitoring Particle Size in Mineral Processing >
Optimizing Mining Processes with Laser Diffraction and Image Analysis >

Nitrogen Physisorption for Surface Area and Microporosity Analysis of Geological Materials >
Microhardness Testing of Minerals and Rocks >
Mercury Porosimetry for Rock Porosity and Pore Size Distribution >
Pilot Plant Furnaces for Coal and Coke Testing >

Ash Fusibility Testing of Coal

Ash fusibility testing is a critical tool for optimizing coal utilization in power generation and metallurgical processes. By determining the characteristic transformation temperatures of coal ash—Initial Deformation (IDT), Softening (ST), Hemispherical (HT), and Fluid (FT)—labs can predict slagging behavior in boilers and gasifiers, ensuring operational safety and efficiency.

Coal ashes with varying mineral compositions exhibit different melting behaviors; for example, high iron or alkali contents lower fusion points. Reliable measurement of these parameters helps operators select suitable coal blends and adjust furnace conditions to prevent slagging and unplanned downtime.

The Carbolite Gero CAF G5 Ash Fusibility Furnace is specifically designed for this application. Key features include:

Heating up to 1600 °C, with inert or reducing atmosphere options to simulate real furnace environments.
Integrated camera and software for continuous image capture and automatic endpoint recognition, minimizing human error.
Compliance with international standards (ISO 540:2008, ASTM D1857/D1857M–18, DIN 51730) for standardized and reproducible results.
Controlled heating rates (e.g. 8 °C/min) to ensure accurate observation of ash cone transformations.

By employing the CAF G5, mining and coal quality laboratories gain precise, reproducible data on ash behavior. The automated image recording not only improves quality assurance but also increases productivity. Its flexibility extends beyond coal, supporting ash fusibility tests on biomass and waste-derived fuels, making it a versatile solution for process optimization.

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GRINDABILITY TESTING IN MINING: BOND WORK INDEX DETERMINATION WITH RETSCH

Accurate Ore Hardness Measurement for Smarter Circuit Design

In the mining and minerals industry, understanding how hard an ore is to grind is essential for designing energy-efficient and cost-effective comminution circuits. The Bond Work Index (BWI) test is the globally recognized method for determining the energy required to grind an ore to a specific particle size. Whether you are designing a new processing plant or optimizing an existing one, knowing the grindability of your material is a critical first step.

Retsch offers an efficient and user-friendly solution for Bond testing with its Drum Mill TM 300 which can be used as Bond Index Tester. This machine is adapted to meet the specific requirements of this standardized procedure.

Why Perform Bond Work Index Testing?

Comminution Circuit Design

Engineers use Bond Work Index values to determine the size and power needs of ball or rod mills. A higher index indicates a harder ore that requires more energy to grind—this directly influences the number or size of mills needed for processing.

Feasibility and Plant Planning

Bond Index data is a standard input in feasibility studies. It helps estimate mill power requirements based on ore throughput and target grind size—making it a key factor in selecting the right equipment and evaluating energy consumption.

Mill Performance Optimization

Over the life of a mine, ore characteristics can change. Tracking the Bond Work Index over time helps optimize mill settings, adjust blending strategies, or forecast equipment wear and maintenance.

Compliance and Reporting

Because the Bond method is widely accepted by banks, engineering firms, and regulatory bodies, performing the test accurately is essential for audits, design validations, and project approvals.

The Retsch Advantage: Efficient and Scalable Testing

Traditionally, Bond Work Index tests were time-consuming and labor-intensive. Retsch simplifies this process by offering:

Dedicated Bond Index Ball and Rod Mills tailored to the standardized procedure.
The Drum Mill TM 300 is configurable for Bond testing, providing high flexibility in lab environments.
Potential integration with software to streamline data handling, such as automatic revolution counting and built-in calculation tools for determining final work index after each cycle.

This level of automation and precision reduces operator workload, increases consistency, and improves turnaround time for grindability assessments—without sacrificing the accuracy required by the Bond method.

For mining professionals, metallurgists, and process engineers, determining the Bond Work Index is essential for proper equipment sizing, energy estimation, and process optimization. With Retsch’s specialized and efficient Bond testing equipment, you gain reliable data faster, with less manual effort, and full confidence in your results. Whether you're designing a greenfield plant or fine-tuning an existing circuit, Retsch delivers the grindability testing solution you can trust.

Drum Mill TM 300

Iron Ore Reducibility Test

Reducibility of iron ore is a measure of how easily an iron ore can be reduced (oxygen removed) to metallic iron, under conditions resembling a blast furnace. The standard test (ISO 4695:2015) involves reacting iron ore pellets or sinter with reducing gas at high temperature and measuring the rate and extent of weight loss (as oxygen is stripped away). The result is typically expressed as a Reduction Index (% reduction at a certain time) or as a rate.

Mining and metallurgical labs perform this test to evaluate different iron ore sources for blast furnace performance – ores that reduce readily will require less fuel and lead to higher efficiency.

This test is crucial for blast furnace feedstock evaluation.

A highly reducible ore will contribute to lower coke consumption in the blast furnace and potentially higher productivity.

If an ore has poor reducibility, it may not be fully reduced in the shaft, leading to lower metallization or more energy needed in the hearth, or it may affect the furnace permeability (because reduction causes expansion or disintegration which can be problematic).

When developing beneficiation processes or comparing lump ore vs. pellets, reducibility is one metric for quality. Pellet manufacturers also track reducibility as quality control, since additives or firing conditions can change it.

The Carbolite Gero IOR (Iron Ore Reducibility) furnace is designed for this test, accommodating the sample basket and providing a controlled gas environment and temperature profile. It likely includes a built-in balance to automatically record weight change, similar to TGA but on a larger scale.

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The IOR furnace can be equipped to run tests in parallel or sequence through automated control of gas and temperature.

Test procedure:

Typically, a sample of sized ore (like 10mm pellets or sinter pieces) is placed in a reaction tube furnace.
The furnace is heated to around 900 °C (ISO 4695 specifies 950 °C) in a flowing reducing gas (usually CO + N₂ or H₂/CO mixtures) for a defined period.
The sample is weighed intermittently or continuously to determine how much oxygen (mass) has been removed at intervals.

Monitoring Particle Size in Mineral Processing (Grind Optimization and Recovery)

In mining, precise control of particle size is critical for maximizing mineral recovery in downstream processes like flotation or leaching. Laser diffraction analyzers provide real-time feedback on grind size (e.g., D80 or % passing 75 µm), enabling operators to adjust mill parameters promptly. Unlike traditional sieving, laser diffraction is faster, automated, and follows ISO 13320 standards, ensuring reliable data.

This method is widely applied in grind circuit control, where maintaining particles within an optimal range (typically 10–100 µm for copper sulfide flotation) enhances liberation and flotation efficiency. If particles are too coarse (>150 µm), minerals remain locked in gangue; too fine (<5 µm), they may reduce recovery or increase reagent consumption.

Case studies show installing online particle size systems improves process stability and recovery—often by 1–2%. Academic research supports this, linking grind size to recovery curves and geometallurgical models. ASTM B822, providing trustworthy measurements.

There is also another example about SYNC and the combination of laser diffraction and dynamic image analysis, to improve energy efficiency and reduce carbon footprint in magnetite and iron ore beneficiation. The key goal is optimizing particle size and magnetic conditioning to enhance downstream processes like flotation. By analyzing particle size and shape from the same sample, the system avoids sampling errors and ensures accurate data.

Read the application note: Magnetite and Iron Ores: Potential Use of Diffraction Particle Size Distributions in Combination with Simultaneous Image Analysis to Achieve Higher Energy Efficiency and Smaller Carbon Footprint

Optimizing Mining Processes with Laser Diffraction and Image Analysis

In mining and geology, particle size distribution directly influences exploration accuracy, processing efficiency, and compliance with environmental standards. From drilling to flotation and construction aggregates, precise characterization is essential to optimize recovery, reduce costs, and ensure sustainability.

The Microtrac SYNC uniquely combines Laser Diffraction (LD) and Dynamic Image Analysis (DIA) in a single instrument, delivering comprehensive data on both particle size and shape. This dual approach empowers operators with rapid, automated, and reproducible results across the entire mining value chain.

Key Benefits:

Exploration & Resource Characterization: Grain size data reveal mineralization patterns and guide drill placement.
Processing & Mill Optimization: Real-time particle size monitoring reduces energy use and improves metallurgical recovery.
Flotation & Leaching Control: Ensures optimal feed size for maximum yield and reduced reagent consumption.
Environmental Monitoring: Tracks tailings, dust, and effluents to comply with strict regulations.
Construction Materials: Provides rapid gradation control for aggregates, enhancing quality and durability.

Why Verder Solutions Matter

Microtrac SYNC for combined LD + DIA particle analysis.
STABINO ZETA for slurry stability and zeta potential monitoring.
Integration with Retsch sample preparation tools ensures representative, contamination-free samples.

With Verder instruments, laboratories and plants gain actionable data that directly improve process efficiency, sustainability, and economic performance.

READ OUR APPLICATION NOTE ⬆️

Nitrogen Physisorption for Surface Area and Microporosity Analysis of Geological Materials

Nitrogen gas adsorption at cryogenic temperatures (77 K) remains a cornerstone technique in geoscience and materials research for determining the specific surface area and microporosity of minerals, ores, and derived materials. Using the Microtrac BELSORP series, researchers and laboratories can gain detailed insight into nanoscale porosity and surface characteristics—crucial for interpreting mineral behavior, adsorption capacity, and processing efficiency.

This method is widely applied across various geological materials such as clays, zeolites, activated carbons, bauxites, shales, and iron ore sinters. It is equally relevant in cutting-edge fields like planetary geology, where mineral porosity offers clues to the formation and alteration of extraterrestrial bodies.

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Micropore and Surface Area Analysis Using Nitrogen Adsorption

Many geological materials, including coals, shales, and zeolites, contain a significant fraction of pores smaller than 2 nanometers. Nitrogen at 77 K can access most of these micropores, while CO₂ at 273 K is often employed to explore ultramicropores (<1 nm) due to nitrogen’s kinetic limitations. However, nitrogen-based BET analysis remains a robust method to determine the overall surface area, capturing contributions from both external surfaces and accessible internal pores (mesopores and select micropores).

Using Microtrac BELSORP analyzers:

Samples are first outgassed to remove moisture and volatile contaminants.

Nitrogen is adsorbed at controlled relative pressures (P/P₀) while the instrument records the adsorption isotherm at 77 K.

Advanced software tools provide BET surface area calculation, micropore/mesopore analysis, and support for various gases including argon (87 K) and carbon dioxide (273 K) for specialized studies.

Standards Methods

Microtrac systems support data evaluation according to international guidelines, ensuring accuracy, reproducibility, and comparability:

ISO 9277:2010/2022 – Defines BET surface area measurements and validation criteria (linearity, C constant, etc.)
ISO 15901-2:2022 – Covers mesopore analysis and pore size distribution via methods such as NLDFT
ASTM D3663 – Standard practice for BET surface area analysis of catalysts, showing cross-industry relevance

Nitrogen physisorption using Microtrac analyzers delivers critical insights into surface area and porosity that cannot be obtained through bulk chemistry or microscopy alone. Whether studying mineral adsorptive capacity, coal rank, or extraterrestrial material, BET analysis offers a standardized, precise view into the nano-scale structure of geological samples—backed by the quality and reliability of Microtrac technology.

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Microhardness Testing of Minerals and Rocks

Precise Measurement of Mineral and Phase Hardness in Geosciences

Micro-indentation hardness testing—using techniques such as Vickers or Knoop under low loads—is a powerful method for evaluating the hardness of individual mineral grains and phases in geological specimens. While commonly used in metallurgy, this technique is equally valuable in the geosciences. QATM microhardness testers, originally developed under the Qness brand, offer precise, reliable measurement solutions that extend beyond metals to polished rock, ore, coal, and planetary samples.

Quantitative Mineral Hardness Characterization

Unlike the traditional Mohs scale, which is qualitative, microhardness testing provides numerical values (e.g., Vickers Hardness Number) for mineral hardness. This allows for more accurate comparisons, the detection of subtle differences between visually similar minerals (e.g., calcite vs. aragonite), and even insights into compositional zoning within a single crystal (e.g., core-to-rim changes in garnet).

Ore Comminution and Geometallurgy

The hardness of individual mineral phases strongly influences ore breakage and grinding behavior. Harder minerals may resist fragmentation, remaining as coarse particles and potentially entrapping softer or valuable phases. Microhardness data supports mineral liberation studies and helps optimize comminution models, directly contributing to process efficiency.

Coal and Shale Mechanics

Microhardness testing is increasingly applied to coal and shale to evaluate their mechanical properties in relation to unconventional gas reservoirs. Measurements provide insights into brittleness, strength, and fracturing behavior, supporting methane recovery and shale gas development.

Planetary and Extraterrestrial Materials

Understanding the microhardness of minerals in meteorites and lunar samples helps assess their abrasion resistance, response to impact events, and susceptibility to space weathering. These studies contribute valuable information to planetary exploration and the interpretation of extraterrestrial material behavior.

Why our equipment?

High-precision indentation at micron scale
Automated measurements and imaging for efficient workflows
Compatibility with polished geological specimens
Absolute hardness values in MPa or kgf/mm², enabling detailed material comparisons

Even fine distinctions—such as different hardness values in polymorphs or across compositional zones—can be captured with QATM instruments, supporting both research and industrial applications.

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Mercury Porosimetry for Rock Porosity and Pore Size Distribution

Mercury Intrusion Porosimetry (MIP) is used to characterize the pore volume and pore size distribution of rocks, ores, and other solid materials by forcing mercury into the pores under pressure.

Porosity is a key property: it’s the storage capacity for fluids in rocks and the determinant of how fluids move (permeability is related to pore throat sizes). While overall porosity can be measured by simpler means (like saturation or helium pycnometry), MIP uniquely provides a pore size distribution (PSD) over a wide range. This is valuable for Reservoir quality evaluation. Given porosity, a sample with predominantly large pores will generally have higher permeability than one where porosity is in micropores. Mercury intrusion gives an idea of effective pore throat sizes controlling flow. Rock typing: Two sandstones might both have 20% porosity, but if one has it mostly in 10 µm pores and the other in 0.1 µm pores, their behavior differs. MIP can differentiate such cases, helping geologists classify reservoir rock types.

In mining and mineral processing, knowledge of pore sizes can influence how one grinds or processes an ore. For example, if an ore’s valuable mineral is contained in matrix that has very small pores, leaching solution might not penetrate well – you’d need to crush finer or pretreat. MIP could quantify those pore entry sizes to inform such decisions.

To sum up, mercury intrusion porosimetry provides geologists and mining engineers with a window into the pore architecture of rocks and materials, quantifying total connected porosity and the size distribution of those connections from a few nanometers up to visible voids. This information is essential for predicting how fluids interact with the material – whether that be oil migrating through a sandstone, or acid leach solution percolating through crushed ore, or simply water entering a building stone and causing weathering.

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BETVLCTOR

Pilot Plant Furnaces for Coal and Coke Testing

Pilot plant furnaces are essential tools for simulating coal and coke processing under controlled laboratory conditions. They enable mining and metallurgical laboratories to replicate industrial coking processes on a smaller scale, providing valuable data for process optimization and coal blend evaluation.

Application Relevance

Coal Blend Evaluation: Test small-scale coke production to predict industrial performance.
Process Optimization: Study carbonization behavior to improve efficiency in steelmaking operations.
Quality Assurance: Assess coke strength, reactivity, and suitability for blast furnaces before full-scale use.
Research and Development: Support development of new coke oven processes and alternative fuels.

Carbolite

Carbolite Gero Pilot Plant Furnaces provide precise control over heating profiles, atmospheres, and batch sizes. This allows mining and steel laboratories to reliably simulate industrial conditions, reduce risks, and ensure that raw materials meet the stringent requirements of metallurgical processes.

Enabling Progress in GEOLOGY AND MINING

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